Safety handle for enclosed switches



Aug. 23, 1960 Filed Nov. 10, 1958 A. BACHMAN ETAL SAFETY HANDLE FOR ENCLOSED SWITCHES 2 Sheets-Sheet 1 Inventors ANA TOLE BACHMAN CHA ES E. McROyTs- Aug. 23, 1960 A. BACHMAN ETAL 2,950,353

SAFETY HANDLE FOR ENCLOSED SWITCHES Filed Nov. 10, 1958 2 Sheets-Sheet 2 FIG. 21

Inventors 74 AN OLE EACH N CHA LES E. 0 R75 by: W

Unit States 2,950,363 Patented Aug. 23, 1960 tine SAFETY HANDLE FOR ENCLUSED SWITCHES Filed Nov. 10, 1958, Ser. No. 772,927

6 Claims. (Cl. 200-50) The invention relates to electrical switch gear and has particular reference to, so-called, safety switches.

A safety switch of the type contemplated is usually enclosed in a protective housing with a door which is openable to provide necessary access to the switch itself.

Additional safety features of such switches include means for automatically latching said door in the closed position when the switch is in its on position; emergency means for overcoming the said latching to permit the door to be opened notwithstanding that the switch is in the on position; means adapted to receive an external locking device for manually locking the switch in either its on or off position and coincidentally preventing opening of the door otherwise than by manually removing said locking device.

In switches of the type visualized the switch control mechanism consists of a knob on the exterior of the door and a control shaft extending from the switch through an opening in the door in a position to be engaged for operation by the knob. While in such position the shaft is adapted to be captured for the purposes of locking and/ or latching the switch and the door as aforesaid and a slot is usually provided in the shaft for co-operating with such means.

The invention proposes to provide a knob for the stated purpose which will serve its intended function more expeditiously and positively than its predecessors.

In particular, the knob of the present invention is easy and hence economical to manufacture.

More specifically, a knob constructed in accordance with the present invention has means for engaging the shaft at a point where it is not weakened by the slot aforesaid.

In addition, the invention also contemplates a knob with shaft-capturing means which is less likely to stick or bind in operation than are the corresponding means of the prior art and to provide a better grip on the shaft for door-locking or latching purposes.

According to the invention, parts constituting such latching and locking means have a rocking action instead of a sliding action as heretofore taught by the prior art, and have claws instead of bolts for capturing the shaft, thereby permitting the use of a smaller slot in the control shaft, and having other advantages that willbecome apparent from the following description of the invention.

A preferred form of the invention will now be described by way of example only with reference to the following drawings wherein:

Figure 1 is a perspective view of an enclosed safety switch showing the relationship of the electrical components, the control shaft and the operating knob, part of the housing being cut away to expose the components.

Figure 2 is an exploded perspective view of a complete operating knob and showing the housing door, the aperture in the door and the control shaft, for clarity.

Figure 3 is a horizontal section of an operating knob along the line 1-1 of Figure 2 with the knob in the on position.

' 19 aforesaid, and in the automatic and manual locking turing position.

Figure 4 is a horizontal section of the knob along the line 11 of Figure 2 with the knob in the oif position. Figure 5 is a vertical section of an operating knob along the line 1111 of Figure 2, showing the manual locking means in operation, the door being closed and the knob in either on or 0-1 position.

Figure 1 shows the relationship of the knob 10 relative to the electrical components 12, the housing 14, the housing door 16, with aperture 17, hinged at hinges 18, and

. means generally indicated by the numeral 19, engaging the control shaft 20 below its slot 21. A number of these parts form no part of the present invention and are introduced in this illustration by way of explanation only. This invention is chiefly concerned with improvements in the knob 10 including its shaft-engaging means devices which, in the present invention, are situated entirely within and constitute parts of the operating knob 10 and this will now be considered in detail.

In Figure 2 the knob 10 is shown exploded with a portion of the body cut away to expose the interior thereof. The knob 10 has a body 22 of plastic or other suitable material having a hollow interior and a short depending skirt 23 adapted to rotate, between positions corresponding to the on and off positions of the switch, in the opening 24' of door plate 24 which is screwed to the housing door 16 in registration with the aperture 17 locating the knob 10 externally on the door 16 in co-operative relation with shaft 20. Located on the inner side of door 16 is the shaft-engaging means or mounting plate 19 which is screwed to the knob body 22 thus moveably securing the knob 10 to the door plate 24 which, as has been pointed out is fixed to the door 16. A mating opening 28 formed in mounting plate 19 operatively engages the shaft 20 and provides access for the shaft 20 to the interior of the knob 10.

Situated inside the body 22 are the various latching, locking, and interlocking devices which will now be described.

Dealing first with the automatic latching or locking device shown in Figure 2 and indicated generally by the letter C, it will be seen to include a shaf -capturing claw 30 situated at free end of arm 32 of bell-crank member 34 which is rockably mounted in the interior of body 22, and is yieldably biased, as by spring 36, into shaft-cap- The other arm of bell-crank member 34 consists of a lever portion 42 in engagement with driver 44 which is slideably carried in the groove 46 of the knob body 22. The driver 44 is formed with a step 48 which follows cam track 56 which is formed in door-plate 24 and constitutes a periphery of its opening 24. The step 43 is also adapted to engage abutments 52 and 54 resulting at the respective ends of cam track 5% when the knob is in either its on or off positions thereby limiting the arc of rotation of the knob 10. Driver 44 is also formed with extension 56 extending through groove 4a to the exterior of body 22 for manual access and operation of said driver. When the knob 10 is turned from say, on to oif position, cam track 50 advances driver 44 to drive claw 30 out of shaft-capturing position (as shown in Figure 4) and when the knob is turned back from the off to the on position driver 44 is free to slide back into the recessed portion of cam track 50 as claw 30 is biased back by spring 36 into its normal shaft-capturing position once more (as is shown in Figure 3). When the claw 39 is in this position, the extension 56 of driver 44 projects outside body 22 and can be manually pushed into said body to drive said claw 30 out of shaft-capturing position, against the influence of spring 36 which will restore said claw 30 back into its shaft-capturing position when said extension is released.

Plunger 58 forms no part of the automatic locking means above but operates to lock the knob in either on or off position when the housing door 16 is open; plunger 58 being slideably mounted in the body 22 and formed with projection 62 for engaging either notch. 64 in door plate 24 when the knob 16 is in either on or off position as is shown in Figure 2. Spring 60 urges plunger 58 into engagement with said notches but when door 16 is closed the said plunger 58 is elevated by step 70 of control shaft 2% to prevent it from engaging in a said notch 64.

Turning now to the manual locking device, Figure 2 shows it in position in the body 22 as consisting of shaftcapturing claw 72 at the end of arm 74 of bell-crank member 76, plunger 78, spring. 69 and spring 36 which is also common to bell-crank member 34. Bell-crank member 76 is rockably mounted in the interior of the body ZZ-co-axially with bell-crank 34 and is normally biased, as by spring 36, to maintain claw 72 out of shaftcapturing position. The other arm of bell-crank member 76 extends as a tiltable lever 82 through the body 22 and terminates on the exterior thereof in a loop 34; said lever being manually tiltable to rock the said claw 72 into shaft-capturing position. When thus tilted, the loop 84 iselevated above the knob body 22 and exposed to receive a locking device 86 by which lever 82 is maintained in the said tilted position with the associated claw 72 engaging shaft 259. abutment 38 which engages with a corresponding abutment on plunger '78. Plunger 78 is slideably mounted in the body 22 for engagement in a notch 64 in door plate 24, when the knob is in either on or off position, but is spring biased out of such engagement by spring 63. When it is desired to lock the knob in either on v or off position the operator tilts lever 82, thereby moving claw 72 of bell-crank 76 into shaft-capturing position (in the slot 21 on shaft 20) and at the same time dopressing plunger 78, by means of the engaging abutments 88 and 9t? into a corresponding notch 64. However, it will be noted that unless the plunger 78' is in position to be received into a said notch 64, the lever 82 cannot be tilted. Conversely, the knob 19 cannot be turned so long as the lever $2 is tilted as shown inasmuch as when it is so tilted, the plunger 78 is necessarily engaged in a notch 64.

Summarizing what has hereinbefore been described, the mounting plate 19 is screwed or otherwise affixed to knob body 22 with the door plate 24 contained and sandwiched therebetween. Said mounting plate 19 also has an opening 2 8 with approximately the same profile as the shaft 20 and, being disposed on the inner side of door 16, receives and hence engages said shaft 20 well below the slot 21 of the latter.

Within the knob 10, the shaft 20 is oriented to receive claws 3t and/ or 72 within its slot 21 and, hence, to be captured thereby; the former claw 30'being biased to capture the shaft 29 while the latter claw 72 is biased by a spring 356, common to both said claws and spring 6t) through plunger '78, out of shaft-capturing position.

The knob lil is rotatable relative to the door plate 24 which is fixed on housing door 16 and its opening 24 provides a perimetrical cam track 50 which is disposed to be brushed by a projecting driver 44 which travels with the knob body 22 and in which it is slideable according to the cam contour or by manual pressure to drive the claw 34) out of shaft-capturing position; the cam 50 being contoured to procure the disengagement of claw 30 from shaft 2% when knob body '22 is in off position or alternately to permit the bell-crank 34 to expel the driver 4 and thus enable the return of claw 33 to shaft-capturing position when the knob is moved to the on position.

When the shaft 2b is captured as in the on position, the opening of door 16 is, of course, automatically prevented by the mechan sm described which can, however,

Formed in the web of bell-crank 76 is.

However, the opening of the door 16 can be further controlled by tilting the lever 82 which is lockable in this position by locking device 86 to procure the engagement of its associated claw 72 with shaft 20 and, at the same time, to procure engagement of plunger 78 in a notch 64 to prevent rotation of the knob between its on and off? positionswhile the lever 82 is so tilted.

The foregoing description is of a preferred embodiment of my invention and is intended to be by way of illustration only. We do not limit ourselves to the specific construction of any features shown and the appended claims are intended to include all changes which do not depart from the spirit of our invention.

What we claim as our invention is:

1. In a safety switch of the type which is enclosed in a housing withan openable door and has a control shaft operable through an aperture in the door to vary the said switch between on atnd off conditions, means governing the openability of said door comprising; a knob with a hollow interior located on the door in cooperative and co-movable relation to said shaft; claws mounted insaid knob for capturing said shaft and thereby preventing the opening of the door, one of said claws being automatically operable and another being manually operable, plungers carried by the knob; a stationary doorplate having notches disposed on said door, and a mounting plate for engaging said shaft and securing said knob to said door; at least one of said notches in said doorplate constituting a socket for said plungers for restraining movement of said knob; one of said plungers being arranged for co-operation with the manually operable claw to enter said socket when the said manually operable claw is in shaft-capturing position and to restrain the operation of said manual claw unless and until the knob is in position to allow said plunger to enter said socket.

2. An operating handle for a safety switch of the type which is enclosed in a housing with an openable door and has a control shaft moveable through an aperture in the door to vary the said switch between on and off conditions, comprising, in combination, a door-plate with notches formed therein fixed to the said door and having an aperture in registration with that in the door; a knob with a hollow interior moveably seated on said doorplate; a mounting plate co-moveable with said knob secured to said knob with said door-plate sandwiched therebetween and maintaining the knob-on said door, said mounting plate having an opening by which said shaft is engaged and providing ingress for the shaft into the interior of the knob; claws mounted in said. knob for capturing said shaft and thereby preventing opening of the door, one of said claws being automatically operable another being manually operable; said automatically operable claw being located at one end of a bell-crank member having an elbow by which it is pivotally mounted and being yieldably biassed into shaft-capturing position; a driver co-moveably carried by said knob in operative relation to said claw; a cam surface constituted by one of the notches on the door-plate aforesaid arranged to intercept said driver and drive said claw out of shaftoapturing position when the knob is moved from on to off position, abutments at either end of the notch bounding the cam surface aforesaid and providing stops engaging said driver for limiting the movement of the knob between on and off positions, said driver also extending to the exterior of the said knob and being manually operable to drive said claw out of shaftoapturing position when the knob is in the on position; said manually operable claw being located at one end of another bell crank member having an. elbow by which it is pivotally mounted oo axially with the other bellcrank member, and yieldingly biassed out of shaft-capturing position; a lever mounted on said further bell crank member integrally with said further claw extending to the exterior of said knob and being manually tiltable to move said claw to capture said shaft; said lever being formed to permit the disposition of a locking device between the knob and the lever when the latter is tilted as aforesaid to maintain said claw in shaft-capturing position; plungers carried by said knob for interlocking with at least one of the notches in the door-plate aforesaid, one of said plungers being operatively related to the lever aforesaid to prevent tilting thereof until said plunger is in position to be received in one of said notchw and being yieldably biassed out of engagement therewith, another said plunger being yieldably biassed to enter and project through one of said notches.

3. In a safety switch of the type which is enclosed in a housing with an openable door and has a control shaft moveable through an aperture in the door to vary the said switch between on and off conditions, means governing the openability of said door comprising; a knob with a hollow interior located externally on the door in cooperative and co-moveable relation to the said shaft; shaft-engaging means co-moveably securing said knob on said door and having an opening providing access between said shaft and the interior of said knob; a claw moveably mounted in the interior of the knob yieldably biased to capture said shaft and thereby to prevent opening of the said door, and means for procuring the movement of said claw out of shaft-capturing position when the switch aforesaid is moved from on to off condition; said shaft-engaging means comprising a plate co-moveably securing said knob on said door and having means for engaging said shaft at a point closer to the switch than that at which it is adapted to be captured by the said claw.

4. In a safety switch of the type which is enclosed in a housing with an openable door and has a control shaft moveable through an aperture in the door to vary the said switch between on and 01f conditions, means governing the openability of said door comprising; a knob with a hollow interior located externally on the door in cooperative and co-moveable relation to the said shaft; shaft-engaging means co-moveably securing said knob on said door and having an opening providing access between said shaft and the interior of said knob; a claw moveably mounted in the interior of the knob yieldably biased to capture said shaft and thereby to prevent opening of the said door, and means for procuring the movement of said claw out of shaft-capturing position when the switch aforesaid is moved from on to off condition; said shaft-engaging means comprising a plate comoveably securing said knob on said door and having an opening conforming to the cross-section of the said shaft and being disposed to engage said shaft at a point closer to the switch than that at which it is adapted to be captured by the said claw.

5. In a safety switch of the type which is enclosed in a housing with an openable door and has a control shaft moveable through an aperture in the door to vary the said switch between on and off conditions, means governing the openability of said door comprising; a knob with a hollow interior located externally on the door in cooperative and co -moveable relation to the said shaft; shaft-engaging means co-moveably securing said knob on said door and having an opening providing access between said shaft and the interior of said knob; a claw moveably mounted in the interior of the knob yieldably biased to capture said shaft and thereby to prevent opening of the said door, and means for procuring the movement of said claw out of shaft-capturing position when the switch aforesaid is moved from on to off condition; said means for procuring the movement of the claw comprising a driver co-moveably carried by the knob in operative relation to said claw and a cam disposed on the door to operate said driver to drive said claw out of shaft-capturing position when the knob is moved from on to off position.

6. In a safety switch of the type which is enclosed in a housing with an openable door and has a control shaft moveable through an aperture in the door to vary the said switch between on and oif conditions, means governing the openability of said door comprising; a knob with a hollow interior located externally on the door in cooperative and co-moveable relation to the said shaft; shaft-engaging means co-moveably securing said knob on said door and having an opening providing access between said shaft and the interior of said knob; a claw moveably mounted in the interior of the knob yieldably biased to capture said shaft and thereby to prevent opening of the said door, and means for procuring the movement of said claw out of shaft-capturing position when the switch aforesaid is moved from on" to 01f condition; said claw being located at one end of a bell-crank member having an elbow and being pivotally mounted in the knob by its said elbow.

References Cited in the file of this patent UNITED STATES PATENTS 1,820,704 Jennings Aug. 25, 1931 2,475,338 Rowe July 5, 1949 2,512,505 Rowe June 20, 1950 2,806,099 Rexroad Sept. 10, 1957 

